The UCC256301 is a fully featured LLC controller with integrated high-voltage gate driver. It has been designed to pair with a PFC stage to provide a complete power system using a minimum of external components. The resulting power system is designed to meet the most stringent requirements for standby power without the need for a separate standby power converter, and with PFC stage running all the time. UCC256301 includes a range of features designed to make LLC converter operation well controlled and robust. This device aims to unburden the LLC designer and allow mainstream applications to benefit from efficiency advantages of the LLC topology.
UCC256301 uses hybrid hysteretic control to provide best in class line and load transient response. The control effort is approximately linear proportional to average input current in one cycle. The control makes the open loop transfer function a first order system so that it’s very easy to compensate. The system is always stable with proper frequency compensation.
UCC256301 provides a high efficient burst mode with consistent burst power level during each burst on cycle. The burst power level is programmable and adaptively changes with input voltage, making the optimization of efficiency very easy.
PART NUMBER | PACKAGE | BODY SIZE (NOM) |
---|---|---|
UCC256301 | SOIC (16) | 9.9 mm x 3.9 mm |
Changes from B Revision (August 2017) to C Revision
Changes from A Revision (August 2017) to B Revision
Changes from * Revision (August 2017) to A Revision
PIN | I/O | DESCRIPTION | |
---|---|---|---|
NAME | NO. | ||
BLK | 4 | I | This pin is used to sense the PFC output voltage level. A resistive divider should be used to attenuate the signal before it is applied to this pin. The voltage level on this pin will determine when the LLC converter start/stops switching. The sensed BLK voltage is also used to adjust the burst mode threshold to improve efficiency over the input voltage range. |
BW | 8 | I | This pin is used to sense the output voltage through the bias winding. The sensed voltage is used for output over voltage protection. |
FB | 5 | I | LLC stage control feedback input. The amount of current sourced from this pin will determine the LLC input power level. |
GND | 11 | G | Ground reference for all signals. |
HB | 14 | I | High-side gate-drive floating supply voltage. The bootstrap capacitor is connected between this pin and pin HS. A high voltage, high speed diode should be connected from RVCC to this pin to supply power to the upper MOSFET driver during the period when the lower MOSFET is conducting. |
HO | 15 | O | High-side floating gate-drive output. |
HS | 16 | I | High-side gate-drive floating ground. Current return for the high-side gate-drive current. |
HV | 1 | I | Connects to Internal HV startup JFET. This pin provides start up power for both PFC and LLC stage. This pin also monitors the AC line voltage for x-capacitor discharge function. |
ISNS | 6 | I | Resonant current sense. The resonant capacitor voltage is differentiated with a first order filter to measure the resonant current |
LL/SS | 9 | I | The capacitance value connected from this pin to ground will define the duration of the soft-start period. This pin is also used to program the burst mode threshold; the resistor divider on this pin programs the burst mode threshold and the threshold scaling factor with BLK pin voltage. |
LO | 10 | O | Low-side gate-drive output. |
Missing | 2 | N/A | Functional creepage and clearance |
Missing | 13 | N/A | Functional creepage and clearance |
RVCC | 12 | P | Regulated 12-V supply. This pin is used to supply the gate driver and PFC controller. |
VCC | 3 | P | Supply input. |
VCR | 7 | I | Resonant capacitor voltage sense |